1. Field of the Invention
The present invention is directed generally to a developer station in an electrographic apparatus, and more specifically to a method and apparatus for setting the toner metering gap therein.
2. Description of the Related Art
In traditional developer stations, for example according to German Patent document DE 31 17 296 C2, what is referred to as a leveling ledge is provided in the form of a rotatable shaft that is halved in regions (see FIG. 1 therein, reference character 42), so that the turning of the leveling ledge enables a setting of the width of a spacing between the leveling ledge and a neighboring developer drum (the hollow cylinder 24 therein). The spacing is varied by turning the leveling ledge and, accordingly, the amount of developer that is applied onto the surface of the developer drum is set.
According to German Patent Document DE 31 18 995 C2, a specific distance is provided between a developer drum and a stripper drum and this, for example, should be adjustable by seating the stripper drum in eccentric bushes. The distance of the stripper drum from the developer drum determines the height of the developer mix from the developer drum. However, the stripper drum constantly rotates with the developer drum.
In the first-cited patent, German Patent document DE 31 17 296 C2, the leveling ledge is constantly rotatable and, thus, adjustable only over the full axial extent. The change of the rotational position of the leveling ledge is constant over the entire axial length.
In the second patent, German Patent Document DE 31 18 995 C2, the stripper drum is fashioned as a constantly rotating shaft, so that a variation of the rotational position in the eccentric bushes here also leads to a change in width of the gap that is constant over the entire axial length of the stripper drum.
Compared to the foregoing, an object of the present invention is to provide a method and an apparatus for setting a metering gap in a developer station whereby the metering gap, as viewed over its axial length, has an adjustable width such that tolerance fluctuations can be compensated.
For achieving this object, the present invention provides an apparatus for setting a metering gap in a developer station, wherein the developer station includes a magnetic drum that has a preceding metering device for the acceptance of a developer mix and for forming a uniformly distributed developer mix, wherein the metering gap is formed between the magnetic drum and the metering device and the metering device is formed by a metering profile, where the metering profile is adjustably held at both axial ends by a respective eccentric such that a setting of the width of the metering gap ensues by turning the respective eccentric, and wherein the eccentrics are adjustable independently of one another.
In further developments, the eccentric is pressed in a housing of the developer station. The eccentric may be pressed in the metering profile. As a preferred embodiment, an application section for a tool is provided at the eccentric so that the eccentric can be turned with the tool. Preferably, the eccentric pitch is formed such that a precision of the width adjustment of the metering gap of approximately 0.02 mm is enabled. A pointer may be provided at each eccentric, this indicating the position of the eccentric with a scale fixed to the housing. As a feature of the invention, an original factory setting of the eccentric is marked on the scale.
In one arrangement, the present developer station includes the magnetic drum with the photoconductor drum arranged following it. A delivery device for the developer mix may be arranged preceding the magnetic drum. A rubber cord that forms a seal is preferably respectively arranged between the two lateral parts of the developer station and the profiles arranged therebetween. These profiles may be fashioned as extruded profiles. In one embodiment, the rubber cord is arranged in a channel that is formed at the lateral part of the developer station. The channel may be of a rectangular crossection. For example, the width of the channel may be smaller than the diameter of the rubber cord and/or that the depth of the channel amounts to at least 50% of the diameter of the rubber cord. A preferred embodiment has the width of the channel amounting to about 90% of the diameter of the rubber cord and/or that the depth of the channel amounts to about 70% of the diameter of the rubber cord. In one example, the width of the channel amounts to about 1.1 mm and/or that the depth of the channel amounts to about 0.8 mm, whereby the diameter of the rubber cord amounts to about 1.2 mm. The rubber cord includes a core of at least one rubber string and an envelope of a textile fabric, for example. The rubber cord is composed of an elastoid and/or that the textile fabric is composed of a polyester weave. The rubber cord is of a round crossection in its unstressed condition.
The present invention also provides a method for setting a metering gap in a developer station, wherein the developer station includes a magnetic drum that has a preceding metering device for the acceptance of a developer mix and for forming a uniformly distributed developer mix, the metering gap being formed between the magnetic drum and the metering device and the metering device being formed by a metering profile, the metering profile being adjustably held at both axial ends by a respective eccentric, and the eccentrics being adjustable independently of one another, in that a setting of the width of the metering gap ensues by turning one of the eccentrics.
As a further aspect of the method, the first eccentric is set independently of the second eccentric. The metering gap may be tilted such that it is diminished in a first region that lies closer to one of the eccentrics and is enlarged in a second region that lies farther away from this eccentric. The width adjustment of the metering gap preferably ensues with a precision of 0.02 mm. The setting of the eccentric can be implemented with the assistance of a pointer connected to the eccentric such that the pointer is set to a mark identifying an original setting. Further, the eccentric may be adjusted with a tool via an application section.
In further detail, according to a first aspect of the invention, a magnetic drum is provided for setting a metering gap in a developer station, the magnetic drum interacting with a preceding metering device for picking up a developer mix and for forming a uniformly distributed developer mix. The metering gap is formed between the magnetic drum and the metering device. The metering device is formed by a metering profile, so that the metering profile is adjustably fixed at both axial ends by a respective eccentric such that a setting of the width of the metering gap ensues by turning the eccentrics, whereby the eccentrics are adjustable independently of one another.
As a result of the eccentric provided at both sides, a tolerance compensation can ensue with respect to the relative position of the adjustable component part (the metering profile here) relative to the stationary component part (magnetic drum here). This tolerance compensation, in particular, ensues according to the inventively provided method.
The metering profile employed according to one embodiment of the present invention can exhibit specific manufacturing tolerances in and of itself that could lead to an imprecise metering gap. These manufacturing tolerances can be compensated by the adjustment of the eccentrics at both sides.
The inventively proposed, variable setting of the metering gap also enables a greater flexibility given different toners and developers. Each toner and each developer requires a different metering gap dimension. When the apparatus, i.e. the developer station, is to be switched to a different toner, for example because the user requests this, then the metering gap can be adapted on site.
The height of the metering gap can be reset, particularly during the course of service work at the developer station. A diminution of the metering gap in at least regions thereof and/or an enlargement of the metering gap in at least regions thereof can thereby ensue dependent on the wear or misadjustment of the developer station components or dependent on the toner to be processed. In particular, a tilting of the gap can ensue to the effect that the gap is made smaller in a first region that lies closer to one of the eccentrics and is enlarged in a second region that lies farther away from this eccentric.
It has proven especially advantageous when the eccentric, on the other hand, is pressed into the housing of the developer station as well as, on the other hand, the eccentric is also pressed into the metering profile. An unintended release of the eccentric is thereby precluded.
An adjustment of the eccentric that is realized by an application section for a tool can ensue with the tool, for example a spanner wrench.
The eccentric pitch is preferably fashioned to be ascending so slightly that a precision of the width setting of the metering gap of approximately 0.02 mm is possible.
A pointer can preferably be provided at each eccentric that indicates the position of the eccentric relative to a scale fixed to the housing, and in one embodiment an original setting of the eccentric undertaken at the factory is marked on the scale.
The developer station that includes the present inventive mechanism is realized having a magnetic drum that is followed by a photoconductor drum; a delivery device for the developer mix also precedes it.
In order to seal joints between lateral parts at the developer station and profiles lying or, respectively, arranged therebetween, a seal is provided according to a second aspect of the invention, which can also be viewed as being independent of the first aspect of the invention (which is the eccentric bearing of the metering profile).
Given traditional seals, silicone strips were applied from the outside after the assembly of the developer station; these, however, are very time-consuming to apply and convey an optically unclean impression. Moreover, this seal was not capable of being fashioned 100% tight at sections that are difficult to access. Sealing parts that are movable relative to one another was not possible at all.
In a preferred exemplary embodiment of the second aspect, the present invention respectively provides a rubber cord, which forms a seal, between the two lateral parts of the developer station and the profiles (movable and non-movable) arranged therebetween. As a result thereof the movable parts or, respectively, profiles, such as the metering profile, can also be provided with a seal, the quality of the seal is noticeably improved compared to known developer stations. The profiles are preferably fashioned as extruded profiles.
In particular, the rubber cord is arranged in a channel that is fashioned at the lateral part of the developer station. This channel preferably comprises a rectangular crossection, whereby the width of the channel is less than the diameter of the rubber cord and/or whereby the depth of the channel amounts to at least 50% of the diameter of the rubber cord.
It is especially advantageous when the width of the channel amounts to about 90% of the diameter of the rubber cord and/or that the depth of the channel amounts to about 70% of the diameter of the rubber cord.
Recited numerically, the width of the channel is preferably 1.1 mm, the depth of the channel preferably 0.8 mm and the diameter of the rubber cord is preferably 1.2 mm.
The rubber cord is composed of a core made of at least one rubber string and of an envelope made of a textile fabric, whereby the rubber string is composed of an elastoid and/or that the textile fabric is composed of a polyester weave.
The rubber cord preferably comprises a round crossection in its unstressed condition.